### speed and order of operations with CDF

Why is the absolute value of the exponential of z:

```
f = fast_callable(exp(z).abs(),domain=CDF,vars='z')
```

about twice as fast as the exponential of the real part of z:

```
g = fast_callable(exp(z.real()), domain=CDF, vars='z')
```

Should I ignore this kind of thing in sage, or is there a good reason in this particular case?

Data:

```
z = var('z')
f = fast_callable(exp(z).abs(),domain=CDF,vars='z')
g = fast_callable(exp(z.real()), domain=CDF, vars='z')
fs(z) = exp(z).abs()
gs(z) = exp(z.real())
sage: timeit('f(4+2*I)')
```

625 loops, best of 3: 2.94 µs per ~~loop
~~loop

`sage: `~~timeit('g(4+2~~*I)')
**timeit('g(4+2*I)')
*

* *625 loops, best of 3: 5.87 µs per ~~loop
~~loop

`sage: `~~timeit('fs(4+2~~

```
I)')
timeit('fs(4+2*I)')
```

625 loops, best of 3: 1.02 ms per ~~loop
~~loop

```
sage: timeit('gs(4+2*I)')
```

625 loops, best of 3: 988 µs per loop